Date: Mon, 19 Jun 2017 06:56:09 -0700
From: "Jim Thomson" <jim.thom@telus.net>
To: <towertalk@contesting.com>
Subject: [TowerTalk] 40 Meter Yagi
<<<< If you use Termans formulae, the coil Q is even less, but this is all
debatable.
## oops. termans formulae depicts the coil Q being a lot more than the k6sti
results,
IE: lower ESR. On one of these small air core hb 40m coils I wound, just 3.5
uh, the ESR per k6sti came out to
.76 ohm using .375 OD CU tubing....and .70 ohm using silver plated .375 cu
tubing.
Using Termans formulae, bare .375 cu tubing came out to .5 ohm ESR. What
the actual ESR is,
who really knows. Q = XL / esr hb silver plated .375 cu tubing coil,
with ends flattened, will handle
a .25-20 SS bolt. SS bolt used to bond the ends of the HB coil onto the
threaded AL hex shaped standoffs.
Other end of al standoff is bolted to the 40M ele with another .25-20 SS bolt.
Anything has to be better than
12 gauge magnet wire, wound tight, on a fiberglass or pvc form.
Jim VE7RF
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